An important goal of chromatography is a complete separation of components in a mixture. Therefore, the field of chromatography is continually striving to increase the efficiency of separating components in order to improve resolution and to permit better isolation of different components.
In particular, there is an increasing demand for the better isolation of enantiomerically pure forms of biologically active chiral compounds in order to investigate relationships between the stereochemistry of these compounds and their biological activity. Therefore, the individual enantiomers should be isolated efficiently, with high optical purity, and in sufficient quantity to perform biological, clinical, or other tests and then, perhaps, to produce commercial amounts of the enantiomer if the test is successful. Chromatography on chiral stationary phases has been recognized as a useful tool in achieving these goals and is now established as an acceptable method for this purpose.
Among the myriad of chiral stationary phases developed and studied since the 1980's, derivatized cellulose-based and amylose-based stationary phases are known to be efficient and versatile chiral sorbents for the chromatographic resolution of enantiomers. Such cellulose-based and amylose-based sorbents show very different selectivities depending on the devitalizing groups on the cellulose and amylose. (Francotte & Wolf, Journal of Chromatography, 595 (1992) 63-75).
The effort to achieve greater separation of enantiomeric mixtures has focused on the stationary phase used, which, as mentioned, is often a cellulose or amylose derivative. However, the mobile phase used for the separation generally is not discussed at length. Typically, the mobile phase used is hexane-isopropanol (9:1). Hexane/ethanol eluents are also known. (Chiral Technologies, Inc.)
With current methods, separation and resolution of enantiomeric mixtures is difficult. Therefore, the art of liquid chromatography would be advanced if greater separation and resolution between enantiomers could be obtained.